Hemodynamic effects of nitroprusside and hydralazine in experimental cardiac tamponade

Cardiac tamponade is associated with decreased cardiac output and increased systemic vascular resistance. Thus, vasodilator drugs might lower systemic resistance and increase cardiac output. Three groups of dogs were studied during tamponade. Group I received nitroprusside only; group II received blood transfusion and then nitroprusside; group III received hydralazine. In group I, nitroprusside lowered right artrial pressure and systemic resistance; cardiac output was unchanged. In group II, transfusion raised right atrial pressure but not cardiac output. Then nitroprusside raised cardiac output significantly. Hydralazine decreased right atrial pressure less than nitroprusside but decreased vascular resistance and raised cardiac output. Both nitroprusside and hydralazine decreased systemic vascular resistance during tamponade, but only hydralazine raised cardiac output probably because of its lesser effect upon the capacitance vessels. Nitroprusside maintained cardiac output during tamponade despite lowered right atrial pressure but increased cardiac output only after transfusion.     

Effects of potassium depletion on renal tubular chloride transport in the rat.

Potassium depletion (KD) causes renal chloride-wasting. To investigate the effects of KD on renal tubular reabsorption of chloride, balance, clearance, micropuncture, and microinjection studies were performed on potassium-depleted rats. KD was produced by omitting potassium from the diet and by administration of DOCA on days 2 and 3; rats were studied on days 9 to 12. Diets were chloride-free in both control and KD groups. In the KD group, balance experiments confirmed greater chloride depletion and continued chloride-wasting, and clearance studies showed an increased FECl. Muscle potassium was reduced by 27% as compared to control. Whole kidney and single nephron GFR were reduced in KD rats to 72 and 74% of control. Fractional (6 +/- 6% vs. 22 +/- 4%, P less than 0.05) and absolute chloride reabsorption in the proximal tubule was not different. Fractional reabsorption of delivered chloride was reduced in the loop of Henle (92 +/- 0.8% in KD vs. 95 +/- 0.7% in control, P less than 0.02). Transtubular chloride ratio (0.28 +/- 0.02 vs. 0.21 +/- 0.02, P less than 0.02) was increased at the early distal tubule. Fractional delivery of chloride (8 +/- 0.9 vs. 5 +/- 0.5%, P less than 0.02), and fluid (26 +/- 1 vs. 22 +/- 1%, P less than 0.05) were also increased in KD at the early distal tubule. Recovery of chloride 36 injected into late distal tubules was 88 +/- 1% on a normal chloride intake, 62 +/- 2% in chloride depletion, and 88 +/- 2% in potassium and chloride depletion. Thus, KD depresses chloride reabsorption in the proximal tubule and in the loop of Henle, and it decreases chloride 36 efflux from the collecting duct.     

Carcinoma of the lung in patients under 40 years of age

Bronchogenic carcinoma in the young population (40 years of age or less) is reported to present in an advanced stage and to have a virulent course. Between 1969 and 1979, 101 patients (65 men and 36 women) presented with cancer of the lung. Their mean age was 36.2 +/- 3.9 years (range 18 to 40 years). Eighty-seven percent had a history of cigarette smoking. Fifty percent of the patients had a strong familial history of malignancy of several organs. The interval between onset of symptoms and diagnosis was 4.01 +/- 3.48 months (3.56 +/- 3.34 for the surgically treated group and 4.16 +/- 3.53 for the nonoperated or unresectable group). Diagnosis was made at bronchoscopy in 32 patients, during thoracotomy in 30 patients, during nodal biopsy in 28 patients, and on cytologic examination of the sputum in 9 patients. The most common cell types were adenocarcinoma in 39 patients, squamous carcinoma in 29 patients, and oat cell carcinoma in 18 patients. Eighty-six patients (the majority) presented in stage III, whereas 9 were in stage I and 6 were in stage II. Twenty-seven patients (26.7 percent) underwent resection for cure, whereas 18 patients were inoperable at surgery. Eighteen of the surgical patients had adjuvant radiotherapy, and chemotherapy, immunotherapy, or both. The average length of survival for the nonresected patients was 7.12 +/- 5.9 months (range 1 to 36 months) and the actuarial survival was 1.5 percent at 36 months. The survival for the surgically managed patients was 56.1 +/- 52.6 months (range 3 to 168 months) or 48 percent at 36 months. At 46 to 168 months after treatment, the only survivors were 13 patients who were surgically managed. Stage III patients had longer survival after surgery (24.1 +/- 24.6 months to 7.09 +/- 5.90 months; range 3 to 74 months and 1 to 36 months, respectively). The survival at 5 years for patients with stage I disease was 78.8 percent, stage II disease 66.6 percent, and stage III disease, 3.6 percent. Early diagnosis and aggressive surgical management are necessary to improve the survival of patients with bronchogenic carcinoma under 40 years of age.     

Intestinal circulation during inhalation anesthesia

This study was designed to evaluate the influence of inhalational agents on the intestinal circulation in an isolated loop preparation. Sixty dogs were studied, using three intestinal segments from each dog. Selected intestinal segments were pumped with aortic blood at a constant pressure of 100 mmHg. A mixture of 86Rb and 9-microns spheres labeled with 141Ce was injected into the arterial cannula supplying the intestinal loop, while mesenteric venous blood was collected for activity counting. A very strong and significant correlation was found between rubidium clearance and microsphere entrapment (r = 0.97, P less than 0.0001), suggesting that the shunting of 9-microns spheres through the intestines reflects the arteriovenous shunting of blood. Nitrous oxide anesthesia was accompanied by a higher vascular resistance (VR), lower flow (F), rubidium clearance (Cl-Rb), and microspheres entrapment (Cl-Sph) than pentobarbital anesthesia, indicating that the vascular bed in the intestinal segment was constricted and flow (total and nutritive) decreased. Halothane, enflurane, and isoflurane anesthesia were accompanied by a much lower arteriovenous oxygen content difference (AVDO2) and oxygen uptake than pentobarbital or nitrous oxide. Compared with pentobarbital, enflurane anesthesia was not accompanied by marked differences in VR, F, Cl-Rb, and Cl-Sph; halothane at 2 MAC decreased VR and increased F and Cl-Rb while isoflurane increased VR and decreased F. alpha-Adrenoceptor blockade with phentolamine (1 mg . kg-1) abolished isoflurane-induced vasoconstriction, suggesting that the increase in VR was mediated via circulating catecholamines.(ABSTRACT TRUNCATED AT 250 WORDS)     

Drug effects upon force and duration of response during fixed-ratio performance in rats

Rats responded on a tandem FR24CRF CRF CRF CRF schedule of water reinforcement by paw-pressing a silent, isometric, force-sensing manipulandum. Oral dose ranges of d-amphetamine, chlordiazepoxide, chlorpromazine, and dantrolene were evaluated for their effects on this schedule-controlled behavior. Peak force, duration and interresponse time (IRT) of individual responses were recorded with a laboratory computer system. Conjoint examination of these three dependent variables revealed that the intensitive measures of response (i.e., peak force and duration) provided information about drug effects that could not be detected with the conventional IRT measure alone. More specifically, peak force was elevated by d-amphetamine at 1.6 mg/kg during the FR component, but IRT was unaffected at this dose. At 3.2 mg/kg, d-amphetamine decreased peak force and lengthened IRT during the FR component. Chlordiazepoxide increased peak force up to the highest dose examined (27.0 mg/kg), whereas dantrolene decreased peak force. Chlorpromazine did not affect peak force but did increase response duration. Higher doses of chlordiazepoxide, chlorpromazine, and dantrolene lengthened IRT during the FR component. For all three dependent variables drug effects were generally less pronounced or altogether undetected in the CRF component. The results are discussed in relation to explanatory principles such as rate-dependency and stereotyped behaviors.     

Individual motor unit analysis in the diagnosis of disorders of urethral sphincter innervation.

A technique is described for recording the electromyographic activity of striated muscle in the urethral sphincter. Using a concentric needle electrode and an oscilloscope with a delay line and trigger, individual motor units were isolated and measured. To validate the method as a means of detecting pathology, the results are presented of analysis of the motor units of a group of patients with disturbances of micturition, known to have either cauda equina lesions or pelvic nerve injury. These results are compared with those from a group of controls. In the control group 93% of the motor units were less than 6 ms in duration and 2.0 mv in amplitude. Of motor units recorded from patients with cauda equina or pelvic nerve injury 59% exceeded the control ranges for amplitude or duration. It is concluded that quantitative analysis of individual motor units may be a helpful technique in the investigation of patients with disorders of micturition.